Preparation method of silver-palladium alloy powder

Abstract

The invention provides a preparation method of silver-palladium alloy powder, and belongs to the field of precious metal alloy powder material preparation. The invention provides a preparation method of silver-palladium alloy powder, which comprises the following steps: mixing a reducing agent, a lubricating agent, a palladium nitrate solution, silver nitrate and water for reduction reaction to obtain the silver-palladium alloy powder, the lubricant is a stearic acid lubricant; the reducing agent is ascorbic acid. According to the preparation method, the lubricant is used for replacing a traditional surfactant to serve as a dispersing agent in reaction to prepare the powder, and the variety of the reducing agent is adjusted, so that the obtained powder has monodispersity, particles are spherical, smooth in surface, narrow in particle size distribution and high in alloying degree, and the powder particles are extremely easy to settle and convenient to wash and separate; therefore, the production process is simple, low in cost, short in period and suitable for mass production.

Description

Technical Field

[0001] The present invention relates to the field of preparation of noble metal alloy powder materials, and particularly to a method for preparing silver-palladium alloy powder. Background Art

[0002] Silver has good electrical conductivity and relatively low price compared with other noble metals, so it is widely used in the preparation of electronic circuits. However, in a high-humidity environment and under the action of a direct-current electric field, silver is prone to migration, resulting in a decrease in the insulation resistance of the electrode and short-circuit of the components. Palladium has good stability and long life, and is one of the most effective metals for improving silver migration. Among silver-palladium powders, silver-palladium alloy powder has better physical, chemical and mechanical properties than silver-palladium mixed powder, and has more advantages in the manufacture of high-end components. At present, the main methods for preparing silver-palladium alloy powder include pyrolysis method, direct-current arc plasma method, liquid-phase chemical reduction method, etc. The liquid-phase chemical reduction method has attracted much attention due to its many advantages such as simple technical route, low cost, and suitability for batch production.

[0003] Currently, the commonly used liquid-phase chemical reduction preparation methods for silver-palladium alloy powder generally use traditional dispersants to adjust the properties of the powder. Some of the prepared powders have poor dispersibility, poor sphericity, and low degree of alloying. Affected by the dispersant, the powder is difficult to settle, and it is difficult to wash and remove the dispersant. These problems have greatly affected the sintering characteristics of the slurry printing film layer, the rheological characteristics of the slurry, the fineness, and the dispersion effect of the powder in the organic carrier, and have prolonged the powder production cycle and increased the production cost. Therefore, improving the dispersibility of the powder, preparing silver-palladium alloy powder with spherical shape, high degree of alloying, and easy to wash and separate is an urgent problem to be solved at present. Summary of the Invention

[0004] The present invention provides a method for preparing silver-palladium alloy powder. The silver-palladium alloy powder prepared by the preparation method of the present invention has monodispersibility, spherical particles, and high degree of alloying.

[0005] The present invention provides a method for preparing silver-palladium alloy powder, comprising the following steps:

[0006] Mix a reducing agent, a lubricant, a solution of palladium nitrate, silver nitrate and water to carry out a reduction reaction to obtain the silver-palladium alloy powder; the lubricant is a stearic acid-based lubricant; the reducing agent is ascorbic acid.

[0007] Preferably, the mixing includes:

[0008] (1) Dissolve the reducing agent in part of the water and then drop the lubricant into the obtained solution to obtain a reduction solution;

[0009] (2) Mix silver nitrate and the remaining water and then mix with the solution of palladium nitrate to obtain an oxidation solution;

[0010] (3) Mix the reducing solution and the oxidizing solution;

[0011] There is no sequence for steps (1) and (2).

[0012] Preferably, the method for preparing the palladium nitrate solution includes the following steps:

[0013] Dissolve palladium in nitric acid solution or aqua regia to obtain a palladium nitrate solution.

[0014] Preferably, the lubricant is a stearic acid emulsion with the model TY101 of Jining Tangyi Chemical Co., Ltd.

[0015] Preferably, the mass ratio of the lubricant to part of the water is 0.5 - 2.5:10000;

[0016] The mass ratio of the silver nitrate to the remaining water is 0.1 - 6:60.

[0017] Preferably, the mass ratio of the lubricant to the reducing agent is 0.5 - 2.5:250.

[0018] Preferably, the mass ratio of the mass of the lubricant to the total mass of silver ions in silver nitrate and palladium ions in palladium nitrate is 0.5 - 5:100.

[0019] Preferably, the mass ratio of silver ions in silver nitrate to palladium ions in palladium nitrate is 99.9 - 0.1:0.1 - 99.9.

[0020] Preferably, the time for the reduction reaction is 10 - 120 min.

[0021] Preferably, after the reduction reaction, it further includes:

[0022] Perform solid-liquid separation on the product obtained from the reduction reaction, and then wash and dry the obtained solid to obtain the silver-palladium alloy powder.

[0023] The present invention uses a lubricant to replace the traditional surfactant as a dispersant in the reaction and adjusts the types of reducing agents to prepare powders. Among them, stearic acid selected as the lubricant and dispersant has the following functions: The molecular structure of stearic acid consists of a hydrophobic alkyl chain and a hydrophilic carboxylic acid head group. The hydrophobic end adsorbs on the hydrophobic surface of nanoparticles through van der Waals forces to form an oriented coating layer, and the hydrophilic end extends outward into the water to form a solvated space barrier. This coating layer physically prevents direct contact between particles, thereby inhibiting particle aggregation; the carboxyl group gives the nanoparticle surface a negative charge, and the charged surface attracts counterions to form an electric double layer, which prevents particles from approaching each other through Coulomb repulsion; stearic acid adsorbed on the particle surface reduces the surface energy of the particles and improves the dispersion stability of the particles; stearic acid can preferentially adsorb on the surface of newly formed nanoparticles to inhibit overgrowth, and stearic acid regulates the growth of crystal planes through coordination, affecting the particle morphology; fatty acids are acidic, and the silver-palladium alloying process is also carried out under acidic conditions; in addition, stearic acid has a flocculation effect on particles. Therefore, using a lubricant as a dispersant not only makes the obtained powders monodisperse, but also the particles are spherical, have a smooth surface, a narrow particle size distribution, a high degree of alloying, and the powder particles are extremely easy to settle, facilitating washing and separation. Therefore, the production process is simple, the cost is low, the cycle is short, and it is suitable for large-scale production.

[0024] Sometimes, the amount of traditional dispersant that needs to be added is as high as 25% (the mass percentage of the added dispersant in the product mass) to ensure the quality of the powder. In contrast, only a very small amount (0.5 - 2.5%) of the lubricant needs to be added to prepare high-performance powders, greatly saving the production cost.

[0025] During the reaction process of the present invention, there is no need to adjust the temperature and pH, and the entire reaction can be carried out at room temperature. The reaction can be directly fed, and due to the flocculation effect of the lubricant, the powder can be quickly and naturally settled and washed, reducing the production cycle and being suitable for large-scale production. Description of the Drawings

[0026] Figure 1 SEM image of the monodisperse spherical silver-palladium alloy powder prepared in Example 1;

[0027] Figure 2 EDS image of the monodisperse spherical silver-palladium alloy powder prepared in Example 1;

[0028] Figure 3 XRD pattern of the monodisperse spherical silver-palladium alloy powder prepared in Example 1;

[0029] Figure 4 SEM image of the monodisperse spherical silver-palladium alloy powder prepared in Example 2;

[0030] Figure 5 SEM image of the monodisperse spherical silver-palladium alloy powder prepared in Example 3;

[0031] Figure 6 SEM image of the monodisperse spherical silver-palladium alloy powder prepared in Example 4;

[0032] Figure 7 EDS image of the monodisperse spherical silver-palladium alloy powder prepared in Example 4;

[0033] Figure 8 XRD pattern of the monodisperse spherical silver-palladium alloy powder prepared in Example 4;

[0034] Figure 9 SEM image of the silver-palladium alloy powder prepared in Comparative Example 1;

[0035] Figure 10 XRD pattern of the silver-palladium alloy powder prepared in Comparative Example 1;

[0036] Figure 11 SEM image of the silver-palladium alloy powder prepared in Comparative Example 2;

[0037] Figure 12 XRD pattern of the silver-palladium alloy powder prepared in Comparative Example 2;

[0038] Figure 13 SEM image of the silver-palladium alloy powder prepared in Comparative Example 3;

[0039] Figure 14 XRD pattern of the silver-palladium alloy powder prepared in Comparative Example 3;

[0040] Figure 15 SEM image of the silver-palladium alloy powder prepared in Comparative Example 4;

[0041] Figure 16 XRD pattern of the silver-palladium alloy powder prepared in Comparative Example 4.

[0042] Figure 17 SEM image of the silver-palladium powder prepared in Comparative Example 5;

[0043] Figure 18 XRD pattern of the silver-palladium powder prepared in Comparative Example 5;

[0044] Figure 19 SEM image of the silver-palladium alloy powder prepared in Comparative Example 6;

[0045] Figure 20 XRD pattern of the silver-palladium alloy powder prepared in Comparative Example 6. Detailed implementation manners

[0046] The present invention provides a method for preparing a silver-palladium alloy powder, comprising the following steps:

[0047] A reducing agent, a lubricant, a solution of palladium nitrate, silver nitrate and water are mixed to carry out a reduction reaction to obtain the silver-palladium alloy powder; the lubricant is a stearic acid-based lubricant; the reducing agent is ascorbic acid.

[0048] Unless otherwise specified, the present invention has no special requirements for the sources of the raw materials used, and commercially available products well-known to those skilled in the art can be used.

[0049] In the present invention, the mixing preferably includes:

[0050] (1) Dissolve the reducing agent in part of the water and then dropwise add the lubricant to the obtained solution to obtain a reducing solution;

[0051] (2) Mix silver nitrate and the remaining water and then mix with the solution of palladium nitrate to obtain an oxidizing solution;

[0052] (3) Mix the reducing solution and the oxidizing solution;

[0053] There is no order of priority between steps (1) and (2).

[0054] In the present invention, the dissolution is preferably carried out under the condition of stirring with a glass rod; the dropwise addition is preferably carried out under the condition of magnetic stirring.

[0055] In the present invention, when mixing the reducing solution and the oxidizing solution, it preferably includes:

[0056] Dropwise add the oxidizing solution to the reducing solution.

[0057] In the present invention, the time of the dropwise addition is preferably 1 to 20 min. In specific embodiments of the present invention, the time of the dropwise addition can be 1 min, 5 min, 10 min, 15 min or 20 min.

[0058] The preparation method of the solution of palladium nitrate preferably includes the following steps:

[0059] Dissolve palladium in nitric acid solution or aqua regia to obtain a palladium nitrate solution.

[0060] In the present invention, the palladium preferably includes fine palladium powder or spongy palladium.

[0061] In the present invention, the solid-liquid ratio of palladium to aqua regia is preferably 0.1 to 3 g: 10 mL. In specific embodiments of the present invention, the solid-liquid ratio of palladium to aqua regia can be 0.1 g: 10 mL, 0.5 g: 10 mL, 1 g: 10 mL, 1.5 g: 10 mL, 2 g: 10 mL, 2.5 g: 10 mL or 3 g: 10 mL.

[0062] In the present invention, the mass ratio of the lubricant to the reducing agent is preferably 0.5-2.5:250. In specific embodiments of the present invention, the mass ratio of the lubricant to the reducing agent can be 0.5:250, 0.7:250, 0.9:250, 1.1:250, 1.3:250, 1.5:250, 1.7:250, 1.9:250, 2.1:250, 2.3:250 or 2.5:250; the lubricant is a stearic acid-based lubricant, and the lubricant is preferably a stearic acid emulsion with the model TY101 produced by Jining Tangyi Chemical Co., Ltd.; the reducing agent is ascorbic acid.

[0063] In the present invention, the mass ratio of the lubricant to a part of water is preferably 0.5-2.5:10000. In specific embodiments of the present invention, the mass ratio of the lubricant to a part of water can be 0.5:10000, 0.7:1000, 0.9:1000, 1.1:1000, 1.3:1000, 1.5:1000, 1.7:1000, 1.9:1000, 2.1:1000, 2.3:1000 or 2.5:1000.

[0064] In the present invention, the mass ratio of the lubricant to the total mass of silver ions in silver nitrate and palladium ions in palladium nitrate is preferably 0.5-5:100. In specific embodiments of the present invention, the mass ratio of the lubricant to the total mass of silver ions in silver nitrate and palladium ions in palladium nitrate can be 05:100, 07:100, 09:100, 1.1:100, 1.3:100, 1.5:100, 1.7:100, 1.9:100, 2.1:100, 2.3:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100 or 5:100. The mass ratio of silver ions in silver nitrate to palladium ions in palladium nitrate is preferably 99.9-0.1:0.1-99.9. In specific embodiments of the present invention, the mass ratio of silver ions in silver nitrate to palladium ions in palladium nitrate can be 92:8, 70:30.

[0065] In the present invention, the mass ratio of silver nitrate to the remaining water is preferably 0.1-6:60. In specific embodiments of the present invention, the mass ratio of silver nitrate to the remaining water can be 0.1:60, 1:60, 2:60, 3:60, 4:60, 5:60 or 6:60.

[0066] In the present invention, the time of the reduction reaction is preferably 10-120 min. In specific embodiments of the present invention, the time of the reduction reaction can be 10 min, 30 min, 60 min, 90 min or 120 min; the temperature of the reduction reaction is preferably room temperature.

[0067] In the present invention, the reduction reaction is preferably carried out under stirring; the stirring rate is preferably 100 - 400 rpm. In specific embodiments of the present invention, the stirring rate can be 100 rpm, 200 rpm, 300 rpm or 400 rpm.

[0068] In the present invention, after the reduction reaction, it preferably further includes:

[0069] Performing solid-liquid separation on the product obtained from the reduction reaction, and then washing and drying the obtained solid to obtain the silver-palladium alloy powder.

[0070] In the present invention, the washing liquid used for washing is preferably deionized water; the washing preferably includes:

[0071] Mixing the solid with the washing liquid and then performing stirring and separation;

[0072] The present invention has no special limitation on the number of washing times, and it is sufficient until the conductivity of the solution after washing is close to the conductivity of deionized water;

[0073] In the present invention, the drying temperature is preferably 50 - 100 °C, and the time is preferably 1 - 36 h. In specific embodiments of the present invention, the drying temperature can be 50 °C, 65 °C, 80 °C or 100 °C, and the time can be 1 h, 12 h, 24 h or 36 h.

[0074] The following combines examples to elaborate in detail on the preparation method of the silver-palladium alloy powder provided by the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0075] The lubricant used in the examples and comparative examples is the stearic acid emulsion with the model TY101 produced by Jining Tangyi Chemical Co., Ltd.

[0076] Example 1

[0077] Weigh 5 g of ascorbic acid and dissolve it in 200 mL of deionized water, and add 0.01 g of lubricant to obtain a reduction solution;

[0078] Weigh 29 g of silver nitrate and dissolve it in 60 mL of deionized water to obtain a silver nitrate solution;

[0079] Dissolve 10 g of palladium in 100 mL of aqua regia to obtain a palladium-containing solution;

[0080] Take 1.6 mL of the above palladium-containing solution and mix it with the above silver nitrate solution to obtain an oxidation solution;

[0081] Drop the above oxidation solution uniformly into the above reduction solution, and finish adding it in 5 min. Perform a reduction reaction for 0.5 h at room temperature under stirring at 300 rpm to obtain a silver-palladium alloy powder precipitate;

[0082] The precipitated silver-palladium alloy powder was stirred and washed with deionized water until the conductivity of the solution after washing was close to that of deionized water, and then dried at 65 °C for 24 h to obtain monodisperse spherical silver-palladium alloy powder.

[0083] Example 2

[0084] The difference from Example 1 is that the amount of lubricant is 0.025 g.

[0085] Example 3

[0086] The difference from Example 1 is that the amount of lubricant is 0.04 g.

[0087] Example 4

[0088] The difference from Example 1 is that the amount of silver nitrate is 2.2 g and the amount of palladium-containing solution used in preparing the oxidation solution is 6 mL.

[0089] Comparative Example 1

[0090] The difference from Example 1 is that the lubricant is removed.

[0091] Comparative Example 2

[0092] The difference from Example 1 is that the lubricant is replaced by polyvinylpyrrolidone with an amount of 0.2 g.

[0093] Comparative Example 3

[0094] The difference from Example 1 is that the lubricant is replaced by gum arabic with an amount of 0.2 g.

[0095] Comparative Example 4

[0096] The difference from Example 1 is that the lubricant is replaced by gelatin with an amount of 0.2 g.

[0097] Comparative Example 5

[0098] The difference from Example 1 is that the reducing agent is hydrazine hydrate.

[0099] Comparative Example 6

[0100] The difference from Example 1 is that the reducing agent is ferrous sulfate.

[0101] Performance Test

[0102] (1) Figure 1 This is the SEM image of the monodisperse spherical silver-palladium alloy powder prepared in Example 1. Figure 2 This is the EDS image of the monodisperse spherical silver-palladium alloy powder prepared in Example 1. Figure 3 This is the XRD pattern of the monodisperse spherical silver-palladium alloy powder prepared in Example 1.

[0103] It can be seen from Figure 1 that the silver-palladium alloy powder prepared in Example 1 of the present invention is spherical particles with a smooth surface, no irregular shapes such as flakes and dendrites, and good dispersibility;

[0104] Figure 2 The EDS results of 2 show that the mass ratio of silver to palladium in the silver-palladium alloy powder is about 92:8, which is close to the feeding ratio; the particle size distribution test shows that D10, D50, D90, and D98 of the silver-palladium alloy powder are 0.695μm, 1.463μm, 2.831μm, and 4.100μm respectively, indicating that the powder has a small size, good dispersibility, and a narrow particle size distribution. The specific surface area is measured to be 1.5683m / g, further indicating that the silver-palladium alloy powder has a high sphericity and a smooth surface.

[0105] It can be seen from Figure 3 the XRD results of

[0106] (2) Figure 4 Figure 19 is the SEM image of the monodisperse spherical silver-palladium alloy powder prepared in Example 2, Figure 5 Figure 21 is the SEM image of the monodisperse spherical silver-palladium alloy powder prepared in Example 3.

[0107] It can be seen from Figure 4 and 5 that the morphology, dispersibility, smoothness, etc. of the silver-palladium alloy powder prepared in Examples 2 and 3 of the present invention are close to those of the silver-palladium alloy powder obtained in Example 1, indicating that the amount of lubricant has little effect on the powder preparation.

[0108] (3) Figure 6 Figure 33 is the SEM image of the monodisperse spherical silver-palladium alloy powder prepared in Example 4, Figure 7 Figure 35 is the EDS image of the monodisperse spherical silver-palladium alloy powder prepared in Example 4, Figure 8 Figure 37 is the XRD image of the monodisperse spherical silver-palladium alloy powder prepared in Example 4.

[0109] It can be seen from Figure 6 that the silver-palladium alloy powder prepared in Example 4 of the present invention is spherical particles with a smooth surface, no irregular shapes such as flakes and dendrites, and good dispersibility;

[0110] Figure 7 The EDS results of

[0111] It can be seen from Figure 8From the XRD results, it can be seen that the characteristic peaks of the powder are located between Ag (PDF#87 - 0717) and Pd (PDF#87 - 0637), indicating that it is an alloy powder. The degree of alloying is calculated to be 28.0%. Moreover, the peaks of the powder are narrow and sharp, and no other impurity peaks are observed, indicating high purity and good crystallinity of the powder.

[0112] (4) Figure 9 Figure 5 is the SEM image of the silver - palladium alloy powder prepared in Comparative Example 1. Figure 10 Figure 6 is the XRD pattern of the silver - palladium alloy powder prepared in Comparative Example 1.

[0113] From Figure 9 it can be seen that the silver - palladium alloy powder prepared in Comparative Example 1 is composed of near - spherical particles, with relatively uniform particle sizes, but poor powder dispersibility; from Figure 10 it can be seen that the diffraction peaks of this powder are narrow and sharp, indicating good crystallinity. And the peak positions are located between Ag (PDF#87 - 0717) and Pd (PDF#87 - 0637), indicating that it is an alloy powder. The degree of alloying is calculated to be 6.34%. In addition, no other impurity peaks are present, indicating relatively high purity of the powder.

[0114] (5) Figure 11 Figure 7 is the SEM image of the silver - palladium alloy powder prepared in Comparative Example 2. Figure 12 Figure 8 is the XRD pattern of the silver - palladium alloy powder prepared in Comparative Example 2.

[0115] From Figure 11 it can be seen that the silver - palladium alloy powder prepared in Comparative Example 2 is a mixed powder of near - spherical and other - shaped particles, with extremely uneven particle sizes and slight particle agglomeration; from Figure 12 it can be seen that the diffraction peaks of this powder are narrow and sharp, indicating good crystallinity. And the peak positions are located between Ag (PDF#87 - 0717) and Pd (PDF#87 - 0637), indicating that it is an alloy powder. The degree of alloying is calculated to be 4.52%. In addition, no other impurity peaks are present, indicating relatively high purity of the powder.

[0116] (6) Figure 13 Figure 9 is the SEM image of the silver - palladium alloy powder prepared in Comparative Example 3. Figure 14 Figure 10 is the XRD pattern of the silver - palladium alloy powder prepared in Comparative Example 3.

[0117] From Figure 13 it can be seen that the silver - palladium alloy powder prepared in Comparative Example 3 is a mixed powder of near - spherical and other - shaped particles, with extremely uneven particle sizes and slight particle agglomeration; from Figure 14It can be seen that the diffraction peaks of the powder are narrow and sharp, indicating good crystallinity. Moreover, the peak positions are between those of Ag (PDF#87 - 0717) and Pd (PDF#87 - 0637), indicating that it is an alloy powder. The degree of alloying is calculated to be 5.22%. In addition, there are no other impurity peaks, indicating high powder purity.

[0118] (7) Figure 15 SEM image of the silver - palladium alloy powder prepared in Comparative Example 4 Figure 16 XRD pattern of the silver - palladium alloy powder prepared in Comparative Example 4

[0119] From Figure 15 it can be seen that the silver - palladium alloy powder prepared in Comparative Example 4 has serious agglomeration. Due to the small particle size, the particle shape is not easily distinguishable; from Figure 16 it can be seen that the diffraction peaks of the powder are narrow and sharp, indicating good crystallinity. Moreover, the peak positions are between those of Ag (PDF#87 - 0717) and Pd (PDF#87 - 0637), indicating that it is an alloy powder. The degree of alloying is calculated to be 6.44%, but there are impurity peaks, indicating low powder purity.

[0120] (7) Figure 17 SEM image of the silver - palladium powder prepared in Comparative Example 5 Figure 18 XRD pattern of the silver - palladium powder prepared in Comparative Example 5

[0121] From Figure 17 it can be seen that the particle size of the silver - palladium powder prepared in Comparative Example 5 is small and the particle shape is not easily distinguishable; from Figure 18 it can be seen that the diffraction peak positions of the powder correspond to those of Ag (PDF#87 - 0717) and Pd (PDF#87 - 0637) respectively, indicating that it is not an alloy powder.

[0122] (8) Figure 19 SEM image of the silver - palladium powder prepared in Comparative Example 6 Figure 20 XRD pattern of the silver - palladium powder prepared in Comparative Example 6

[0123] From Figure 19 it can be seen that the particle size of the silver - palladium alloy powder prepared in Comparative Example 5 is large and the particle shape is irregular; from Figure 20 it can be seen that the diffraction peaks of the powder are narrow and sharp, indicating good crystallinity. Moreover, the peak positions are between those of Ag (PDF#87 - 0717) and Pd (PDF#87 - 0637), indicating that it is an alloy powder. The degree of alloying is calculated to be 2.44%, indicating low alloying degree of the powder.

[0124] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing silver-palladium alloy powder, characterized in that: The following steps are involved: Mixing a reducing agent, a lubricant, a palladium nitrate solution, silver nitrate and water to carry out a reduction reaction to obtain the silver-palladium alloy powder; The lubricant is a stearic acid lubricant; and the reducing agent is ascorbic acid.

2. The preparation method according to claim 1, characterized in that: The mixing includes: (1) dissolving a reducing agent in a portion of water and then dropping a lubricant into the resulting solution to obtain a reducing solution; (2) mixing silver nitrate and remaining water and then mixing with a solution of palladium nitrate to obtain an oxidizing solution; (3) mixing the reducing solution and the oxidizing solution; There is no order in which steps (1) and (2) are performed.

3. The preparation method according to claim 1 or 2, characterized in that: The preparation method of the palladium nitrate solution comprises the following steps: Dissolve palladium in nitric acid solution or aqua regia to obtain palladium nitrate solution.

4. The preparation method according to claim 1, characterized in that: The lubricant is stearic acid emulsion model TY101 produced by Jining Tangyi Chemical Co., Ltd.

5. The preparation method according to claim 2, characterized in that: The mass ratio of the lubricant to part of the water is 0.5-2.5:10000; The mass ratio of the silver nitrate to the remaining water is 0.1 to 6:

60.

6. The preparation method according to claim 4, characterized in that: The mass ratio of the lubricant to the reducing agent is 0.5-2.5:

250.

7. The preparation method according to claim 1 or 4, characterized in that: The ratio of the mass of the lubricant to the total mass of the silver ions in the silver nitrate and the palladium ions in the palladium nitrate is 0.5 to 5:

100.

8. The preparation method according to claim 1, characterized in that: The mass ratio of the silver ions in the silver nitrate to the palladium ions in the palladium nitrate is 99.9-0.1:0.1-99.

9.

9. The preparation method according to claim 1, characterized in that: The reduction reaction time is 10 to 120 minutes.

10. The preparation method according to claim 1, characterized in that: After the reduction reaction, the method further comprises: The product obtained by the reduction reaction is subjected to solid-liquid separation, and then the obtained solid is washed and dried to obtain the silver-palladium alloy powder.

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